[Agda] UTF in Ubuntu

[mechvel at scico.botik.ru]

People,

I use emacs 25.2 for Agda under Ubuntu 18.04.
And it draws the arrow  \-->  (the arrow which is in _Preserves_->_)
in a bad way.
Is this a matter of  emacs  or may be,  of graphic programs  used in 
Ubuntu ?

Thanks,

------
Sergei